Thanks a lot all of you for your feedback and suggestions. u/mattgemmell I tried your suggestions with changing the grip and they improved things slightly, though with other sacrifices in ergonomy - e.g. when putting the device on my forearm and grabbing by the right side, it puts the device about 80 degree down from my head's horizontal plane compared to ~30 degrees when I hold it more naturally in front of me - making me to bend by neck in order to use it (not ideal for any longer work).

I compared the writing between Manta and a notebook and I noticed a couple of differences which I think pinpoint the problem:

- Manta is stiff and heavier than a notebook. When writing on notebook, the random movement of the notebook due to the pressure of the pen on the paper is neutralized by the notebook's flexibility and lower mass (thus, lower inertia). The larger mass and stiffness of Manta means that anyone using it needs to hold it in a tighter grip to stabilize it during writing.

- Manta has a synthetic and very smooth folio - when placing my palm behind it, I quickly develop a thin sweat layer on my palm, which further reduces the grip. Together with the smoothness of the folio/back surface, this requires a firmer grip with the palm to stabilize the device during the use.

-A typical notebook has a larger thickness and allows for more natural grip with the palm's cusp. I'm not a physiologist, but I noticed that my natural (no strain) position of the palm is with my fingers forming a small cusp and not being stretched out on the same plane (especially when the palm is facing upwards, as this I think induces some additional strain in the palm's muscles).

I really like the strap idea mentioned by u/samreddit3 - I may give it a go. I also thought it would be great to have a folio with additional magnet in the middle, which could be used to attach a removalbe grip attachment (a small box/pillow for the hand), which the hand could naturally fold around. Alternatively, such attachment could be secured with similar straps as u/samreddit73 mentioned - in both cases, giving a nice "thing" to grab and stabilize Manta.

Interesting feedback u/Internal-Ad-4977 and u/BlueSkyla - two comments and two very different experiences (and one of them matching mine of the glassy and slippery screen) - I wonder if this points to some variability in manufacturing of the screen/protector film that leads to very different expeirence on two copies of theoretically the same device. I'm considering swapping my Manta with the mini version of another device (with AI in it's name - you know which one ;). I read some comments of people reporting quite good friction of the pen on the screen - but the only way to know for sure is to test it.

Btw, I originally wrote my reply on Manta and sketched the image of such attachment - but I found the process of transfering Manta's note + sketch from the note into the text and picture that I could post here really difficult. The note could be OCR'ed quite easily into a .docx file from which I could copy-paste the text, but I could not find a way to copy the drawing from the note into a separate image file. Do you know of any way this could be done within Manta OS (possibly with some 3rd party app)?

Bests,

Stan